THE SESAMOID BONES 65 



appearance, usually in the lower half of the metacarpal region. The 

 swelling is hot and painful to the touch, and pits on pressure. 



Rest should be prescribed for about a month, during which period 

 gentle walking exercise only should be given, and bandages wrung out 

 of hot water applied to the affected limb or limbs. When the swelling 

 ceases to be painful to the touch it may be painted over with tincture of 

 iodine, or a mild blister applied. 



Under this treatment the swelling may subside and entirely dis- 

 appear, but most frequently a new layer of bone forms under the 

 periosteum, and a permanent thickening of the metacarpal region 

 remains. The size of this may be materially reduced by line-firing, and 

 subsequently blistering the affected area. 



Complications may arise during the course of treatment in the form 

 of necrosis of superficial areas of bone, and abscess formation is not 

 uncommon. In the latter cases the general method of treating an 

 abscess should be adopted. 



THE SESAMOID BONES 



There are two of these small bones in each limb. They are placed 

 at the back of the fetlock joint, in the position which has already been 

 indicated in our superficial examination. They are not weight-bearing 

 bones, but, owing to their position, they take upon themselves the 

 function of affording increased leverage to the tendons of the superficial 

 and deep flexors of the digit. 



Each sesamoid bone in shape resembles a three-sided pyramid, the 

 apex of which is directed upwards. Of the three surfaces, the anterior 

 is articular, and responds to that part of the inferior articular surface of 

 the large metacarpal bone which encroaches upon its posterior aspect. 



The posterior surface is convex from above to below and from side 

 to side. Anteriorly this surface gives attachment to the intersesa- 



